Coronary artery disease is the most frequent cause of death in the elderly. The gold standard therapy for acute coronary syndrome (ACS) is early mechanical myocardial revascularization with either percutaneous intervention with stents (PCIS) or coronary artery bypass grafting (CABG). Although studies suggest that elderly patients with ACS may benefit from myocardial revascularization, these reports lack the power to determine optimum invasive myocardial strategy with respect to age, gender, race, comorbidities and geography. Our long range goal is to identify an efficacious invasive treatment strategy for ACS in the elderly. The central hypothesis of the proposed research is that surgical myocardial revascularization improves survival rates in ACS patients aged 65 and older with fewer reinterventions and decreased resource utilization than the more frequently prescribed strategy of PCIS. The principal objectives of this project are to use national Medicare hospital and physician claims from the Centers for Medicare &Medicaid Services to address four specific aims;1) Identify the factors associated with diffusion of mechanical myocardial revascularization over the study period (2002-2006) in Medicare patients presenting with ACS;2) Determine the influence of age, comorbidity presence, race, gender, and geographic location on the selection of mechanical revascularization strategy (PCIS or CABG);3) Compare clinical outcomes and hospital/physician resource utilization with respect to the initial mechanism of mechanical revascularization treatment;4) Determine if age, comorbidity presence, race and/or gender are associated with disparate outcomes within the selected treatment modality in Medicare ACS patients. We will use propensity score methods to control for mechanism of revascularization to reduce bias from selection. Key outcome measures include rates of rehospitalization, reyascularization, nursing home use, morbidity, new onset delirium, mortality, and Medicare hospital/physician expenditures over a four year follow-up period. A Markov model will be used to portray the relative effects of the two procedures. These results will guide future study design for treatment of ACS in the elderly.